If your air conditioning system won't turn off, there are most likely malfunctioning mechanisms, such as a faulty thermostat or fan limit switch, frozen evaporator coils, electrical issues, or incorrect thermostat or fan speed settings.
The Short Answer Is: When your air conditioning system keeps running and never seems to shut off, the problem could be linked to a number of malfunctioning components – frozen evaporator coils, a clogged air filter, a bad electrical relay switch that needs to be replaced, the fan blowing constantly, dirty condenser ...
This can be due to low refrigerant levels, poor circulation, dirty coils, power issues at the outdoor unit, setting the AC unit temperature too low at night, or power issues at the condenser.
It could be the wrong thermostat setting is being used, a clogged air filter or your thermostat itself is no longer working properly. When you have a heating system not shutting off, this issue makes it difficult to maintain the desired temperature inside the home.
Under normal conditions, an air conditioner running in a properly sized system should cycle for about 15-20 minutes before shutting off. This length of time allows it to cool the air effectively, reach the desired temperature, and then turn off to save energy.
Here's the thing: It's normal for your AC to run continuously during hot summer months. You see, on extremely hot days—we're talkin' high 90s to 100s—your system needs to keep up with the incoming heat. To do that, it will run longer in order to maintain a constant, desired temperature in your home.
Your AC might not cool properly due to thermostat issues, an undersized unit, or extremely high outdoor temps—so check those first. Keep an eye on airflow—replace clogged filters every 3 months, and make sure vents and ducts aren't blocked for efficient cooling.
Check the thermostat.
There may be a wiring problem or worn batteries. If changing the batteries doesn't work, you will likely need a new thermostat. Contact your service technician to set that up.
There are a number of reasons why your air conditioner might be running but not cooling. It could be an issue with the thermostat, the compressor, or the evaporator coils. Or, it could simply be clogged with dust and debris, which is preventing it from working properly.
If the temperature is set to 74°F but the thermometer shows 78°F, you will have to recalibrate the thermostat to account for this 4-degree deviation. Even with older AC units or furnaces, you might have to recalibrate your thermostat from time to time.
If your AC unit is experiencing electrical problems, it can cause the system to run continuously, even after reaching the desired temperature. Faulty wiring or a malfunctioning thermostat system fan can be the culprits.
Most modern thermostats will have a clearly marked reset button inside the panel. It's usually small and recessed, so you might need a pointed object like a paperclip to press it. For those wondering specifically how to reset air conditioner thermostat models, the process is generally the same.
This can happen due to a clogged air filter, low refrigerant levels, or a faulty thermostat. If you suspect a frozen coil, turn off the AC entirely and allow the ice to melt naturally. Once thawed, troubleshoot the underlying cause to prevent refreezing.
Malfunctions affecting different system components can prevent the conditioner unit from shutting down as expected, such as a clogged air filter, a frozen evaporator coil, a faulty electrical relay switch, a dirty condenser coil, a constantly blowing fan, a bad thermostat, low refrigerant, and other HVAC system repair ...
Connect the red wire of the multimeter to the red wire of the thermostat and the black wire of the multimeter to the black or white wire from the thermostat. A functioning thermostat should have readings close to zero or zero. If not, there is a problem with the thermostat.
Check Your Temperature Setting
If your thermostat won't turn off heat, check the temperature setting to the compare temperature. If it's greater than the room air temp, your furnace will keep operating until it reaches your desired temp.
A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
Changing Your Thermostat Settings Increases Wear
So if you're constantly tinkering with your thermostat, you're forcing those systems to cycle on and off, increasing usage and overall system stress. This can lead to more maintenance, repairs, and a quicker need for replacement.
For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.
Clean your Air Filters, Vents, and Ducts – A clogged air filter will struggle to meet the thermostat's set temperature since the dirt and debris buildup prevents air from circulating through the vents. And as airflow into living spaces drops, so do comfort levels.
When temperatures outside become higher than 100 degrees Fahrenheit, the air conditioning system can consume more energy and begin to malfunction or fail. Most air conditioning systems are designed to function with outside temperatures of 100 degrees or less.